Virulence of four fungicides to Phytophthora infestans was tested by a radial growth assay on fungicide-amended agar and Virulences of flumorph and metalaxyl were the strongest. EC50s of the two fungicides were 1.55 μg*mL-1 and 1.63 μg*mL-1 respectively. EC50 of propamocarb was 5.43 μg*mL-1. Virulence of fosety-A1 was the weakest. EC50 of the fungicide was 246.58 μg*mL-1. But flumorph markedly affected emergence of potato. So, fungicides of metalaxyl and propamocarb were selected as seed coating effective ingredient of seed coating controlling late blight. Seed coating of the concentration tested on seed pieces could inhabit but not kill pathogen in seed pieces in the laboratory. But leaflets collected from plants 20 days after emergence, which come from seed pieces with seed coating, could be infeceted by P. infestans in the laboratory.%为了研制防治马铃薯晚疫病的种衣剂,利用菌落直径法测定了4种内吸性杀菌剂对致病疫霉菌的毒力并检测了它们对马铃薯出苗的影响.测定结果表明,灭克锰锌和甲霜灵对晚疫病菌的毒力最强,其中EC50s分别为1.55 μg*mL-1和1.63 μg*mL-1;霜霉威对晚疫病菌的毒力次之,其中EC50为5.43 μg*mL-1;乙磷铝对晚疫病菌毒力最差,其EC50为246.58 μg*mL-1.但是由于灭克锰锌严重影响马铃薯出苗率,所以,甲霜灵和霜霉威被选为防治马铃薯晚病种衣剂的有效成分.室内接种薯片培养试验证明,高浓度(800 μg*kg-1)种衣剂对薯片上晚疫病菌的控制作用很强,持效期至少1个月以上.但室内试验证明利用种衣剂处理薯片,并不能控制苗期晚疫病菌对马铃薯叶片的侵染.
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